Light Emitting Diodes (LEDs) are semiconductor devices that convert electricity into light using characteristics of compound semiconductors so as to enable transmission/reception of signals, or that are used as a light source. Group III-V nitride semiconductors are highlighted as core materials of light emitting devices such as, for example, LEDs or Laser Diodes (LDs) due to physical and chemical characteristics thereof.
The LEDs are eco-friendly because they do not include environmentally harmful materials such as mercury (Hg) that are used in conventional lighting devices, e.g., fluorescent lamps and incandescent bulbs. The LEDs also have several advantages, e.g., long lifespan and low power consumption. As such, conventional light sources are being rapidly replaced with LEDs.
Meanwhile, a conventional light emitting device package is configured such that several layers having different coefficients of thermal expansion are stacked one above another. The difference in coefficients of thermal expansion may lead to the destruction of the light emitting device package.